Middleware integration testing with JUnit, Maven and VMware, part 1 (of 3)
For Deployit, XebiaLabs' automated deployment product for Java EE applications, we are always building and modifying integrations with middleware systems such as IBM WebSphere, Oracle WebLogic and the JBoss application server. These integrations are small enough so that they can be rearranged to get many different deployment scenarios. A typical step, as we call these integrations, would be "Create WebSphere datasource" or "Restart WebLogic Server". So how do the test that code?
We've had some success using FitNesse and VMware to do integration tests on our deployment scenarios. But there were a few problems with this apporach:
- We could only test complete deployment scenarios in this way. If we wanted to test just a single step, we had to make a deployment scenario that used that step just to be able to test it.
- Because FitNesse does not provide any feedback while a test is running and the steps, let alone the deployment scenarios, can sometimes take a while to execute, there was little feedback on the progress.
- While it is possible to debug a FitNesse Fixture using Eclipse the process is not very convenient when debugging a technical component such as this step.
- To verify that a deployment scenario has executed succesfully we had to extend our FitNesse Fixture often. And while debugging code under test in FitNesse is complicated enough, debugging a Fixture is even harder!
Clearly we needed a different approach if we wanted to develop new steps easily.
From FitNesse to JUnit
First of all we decided to ditch FitNesse as our testing framework. While it might be a very nice to tool do user acceptance testing and allow end users to write (or at least understand) tests, the technical nature of our product already ensured that we would not have tests for non-technical end-users. Coupled with the problems that FitNesse was giving us, this was enough reason to look to the ubiquitous JUnit. Clearly we are not writing unit tests but the JUnit framework lends itself to any kind of automated code testing. To differentiate these integrations test from the regular JUnit tests we choose classnames ending in Itest. This made sure that a regular Maven build would not execute them; by default the Surefire plugin only executes tests whose classname ends in Test (with a capital T).
Basic test approach
The basic approach used in our Itests is like this:
- Assert that a Java EE configuration (for example a datasource or a deployed application) does not exist.
- Execute the step that creates the Java EE configuration.
- Assert that the Java EE configuration does exist.
- Assert that the properties of the Java EE configuration (for example the datasource URL) have the expected values.
- Execute the step that destroys the Java EE configuration.
- Assert that the Java EE configuration no longer exists.
One could argue that this test actually tests two pieces of code: the create-step and the destroy-step. But a test for the correct destruction of the resource needs to set it up first anyway. And a test that creates a resource needs to clean up after itself to allow the next test to run correctly. This does mean that tests are dependent upon the previous test cleaning up correctly, but I will show in a later blog how you can use VMware to mitigate this problem.
Asserting that resources are created correctly
The hardest part of this approach is asserting that a Java EE configuration exists (or does not exist) and has the expected properties. For this we must inspect the configuration. Unfortunately each of the three application servers mentioned requires a different method do that.
Inspecting the IBM WebSphere configuration
To inspect the IBM WebSphere configuration we execute the wsadmin script below and then parse the output to build a Map<String,String> of the properties of the object that is pointed to by the containment path. If the script exits with a non-zero exit code we know that the object does not exist in the configuration.
# Read command line arguments containmentpath = sys.argv.pop(0) # Get object ID by containment path objectid = AdminConfig.getid(containmentpath) if objectid == "": print "Object with containment path " + containmentpath + " not found" sys.exit(1) # Print object properties print AdminConfig.show(objectid)
Inspecting the Oracle WebLogic configuration
Oracle WebLogic has a concept very similar to the containment path of IBM WebSphere but there is no specific name for that concept. So in the WLST script you see below we also call it a containment path. Apart from the fact that WLST requires you to connect to the administration server inside the script while wsadmin does the connecting for you based on its command line parameters, the script for WebLogic does the same work as the script for WebSphere:
# Read command line arguments scriptname = sys.argv.pop(0) username = sys.argv.pop(0) password = sys.argv.pop(0) url = sys.argv.pop(0) containmentpath = sys.argv.pop(0) # Connect to the WebLogic admin server connect(username, password, url) # List the properties of the object ls(containmentpath) # Disconnect and exit disconnect() exit()
Inspecting the JBoss configuration
JBoss does not have a Python-based administrative scripting interface but it does have twiddle. Twiddle's query command allows us to test for the existence of an MBean while the get command allows us to retrieve a property of an MBean. There is no command to get all the properties of an MBean but twiddle executes so fast that is not a problem to execute it multiple times.
To be continued...
All this allows us to verify that the configuration has been created correctly, but it still does not tell us whether an application can really use that configuration. I will discuss how to do that in the next part (but I promise you I won't make a series as long as the JPA implementation patterns series ;-)). And I'll also explain how Maven and VMware fit into all of this.